Last week's riot at HMP Birmingham is another reminder of the impact of ruinous cuts to front line prison staff on safety in jails. The outworking of this institutional vandalism was all too obvious to my review team as we visited dozens of prisons in the course of our work this year.

Our focus then was on the dangers posed by Islamist extremists. We felt that far too many areas within prisons had become "ungoverned spaces" with the absence of any uniformed authority to challenge that pernicious ideology.

Front line staff gave graphic accounts of how extreme violence had become normalised and told us of their huge sense of frustration that far from being instruments of rehabilitation, they were...